820-01700 no touchbar, no usb, no kb backlight

[neyleralejandro]

Hello, I received a laptop 820-01700, the touchbar does not work, there is no brightness on the keyboard and it does not recognize the usb ports either.

I already restored with dfu in appleconfigurator and always the same result.

I also tried another topcase and it makes the same error

diode mode compare with ic donnor board and same measures

 

[2informaticos]

First of all, welcome to the forum!

Any history available?
You mention different issues, which can't be related by the same power rail, or signals group.
Machine charges from USB-C ports, but no external device is recognized?
All ports have the same behavior?

Check if you get voltage at L3500 and LB700, when external USB-device is inserted into corresponding ports.

ALS works correctly?
Touchbar and keyboard backlight may be caused by non-working ALS.
R8435/36/46 have the correct values?
Post D8450 voltage (both pins) with keyboard backlight sheet connected.

All voltages and signals on touchbar connectors have the same values like good board?

 

[neyleralejandro]

hi, laptop comes from another shop. board looks good, no water damage

owner says keyboard doesnt work , after measure i found DZ6701 reheat, after change DZ6701 keyboard works again. but a lot of problems, touchbar, bcklight keyboard, and usb devices

L3500 and LB700 voltage is 0 , with and without USB device connected
All ports have the same behavior


r8435/36 10ohm
KBDLED_CATHODE1 0.05V
KBDLED_CATHODE2 O.4V

R8446 5.1V both pins
D8450 5.1V both pins


i found on
R5103
PP1V8_SLPS2RSW_DFR 0.99V
DFR_TOUCH_RESET_L 0V

 

[2informaticos]

"L3500 and LB700 voltage is 0"
Obly one must get voltage at a time, depending where the USB device is connected.
Unless both left/right sides are used at same time; then both coils must get voltage.
Check U3500, UB700 and adjacent components.

"ALS works correctly?"
???

"PP1V8_SLPS2RSW_DFR 0.99V"
Check U5104 voltages; you may need to change it.

 

[neyleralejandro]

Hi bro, ALS is working,

L3500 and LB700 V0 when connect device

 

[neyleralejandro]

update: after replace U5104 touchbar working perfect but no bkl on keyboard

also replace
U3500 / Q3501
UB700 /QB701
no lucky no usb recognize

 

[2informaticos]

Did you chck power and enable signals for U3500 and UB700?

 

[neyleralejandro]

UB700

PP5V_USBCT_VCC 5v
UPC_T_5V_EN_R 0V

after check UB740

PP3V3_G3H_T 3.3V
PM_RSMRST_L 3.3V
UPC_T_5V_EN_R 0V
UPC_T_5V_EN 0V

 

[2informaticos]

U3500, or UB700 get enable signal ONLY when external device is connected into corresponding port; U3500 controls left side.
Of course, 5V must be present always at their pins 19 & 20.

Enable signals come from CD3217 chips.

Should be good to check diode mode to ground on the USB connectors.
Do you have S-UEM2 tool?

What was the reason to change UB740?

 

[neyleralejandro]

hi , again

Of course, I measure the voltage by connecting a USB device to the corresponding port. 5V are present on 19 &20pins. I don't remember mentioning the change of the UB740 ic.

I don't have the tool

 

[2informaticos]

Aaaah sorry, you've said check, not change.

Seems that CD3217 chips don't detect the external devices.
This problem may be caused by incorrect values on data lines.
As I said, need to check diode mode to ground the USB connectors (J3300/JB500).

 

[neyleralejandro]

diode mode measue are the same a working board

 

[2informaticos]

Is the battery charging on all USB-C ports?
Check in both directions.

Try SMC reset, also PRAM reset.
Just in case, change L/D8450.

Check U8472 voltages; remove it and solder 1-10K resistor between pads 4 & 5.

 

[neyleralejandro]

yes, battery charge on all usb-c ports.

if i connect a usb-c 9 in 1 adapter and connect charger to 9 in 1 adapter and adapter to laptop usb devices are recognize.

 

[neyleralejandro]

A friend told me that he had a similar case and that he had to change cd3217, I listened to him and replaced the 4 cd3217 but without luck, it still does not recognize usb devices

 

[2informaticos]

Not easy to work on boards with previously repair atempts.
There may be just a simple resistor, or trace, intentionally damaged.

The detection of the USB devices is based on the CC1/2 lines.
Some information you can find here:

Community - Silicon Labs

The Silicon Labs Community is ideal for development support through Q&A forums, articles, discussions, projects and resources.

community.silabs.com

Once corresponding CD3217 chip detects the USB device, it should enable its 5V power supply; UPC_X_5V_EN, for example.